Junction-free copper wires with submicron linewidth for large-area high-performance transparent electrodes

Abstract

Metal wires with submicron linewidth are important building blocks of a high-performance transparent electrode (TE). However, junction-free metal wires with a small width (below 1 μm) usually relate to high-cost technology, additional welding procedures, or severe undercut, which limit scalable, cost-effective fabrication. Here, copper (Cu) wires with a small linewidth of 550 nm have been successfully fabricated by the scalable technology of electrospinning and wet etching. Good adhesion of masking templates to the substrate suppresses the negative effect of an undercut. The improved bonding comes from the adhesive nature of poly(vinyl butyral) (PVB) and a versatile non-thermal solvent annealing procedure. The best Cu wire TE has a sheet resistance, R_s of 15.9 Ω □⁻¹ at transmittance, T = 90%. The method here also supports preparing a flexible large-area (33 cm × 21 cm) TE. Cu wires on polyethylene terephthalate have equivalent peeling resistance, but much better mechanical flexibility, compared with ITO. Incorporation of this TE into touch screens and QLEDs verifies its application potential.